This invention relates to busways enclosing busbar conductors in metal housings for carrying high current electrical power and particularly relates to forming an elbow for said housing to seal the busbar or busbars against intrusion of moisture at a bend, such as a ninety degree bend, in the busbars.
Known busway systems furnish runs of busbars from sources such as power transformers through plant buildings to distribute medium voltage power to high current draw devices such as motors. The busways typically present a rectangular cross-sectional housing made of sheet metal such as steel, aluminum or stainless steel. Inside the busways insulators support and space the busbars, in phase, from one another and the enclosure walls. In some installations, the busbars are wrapped in insulation material and abut the walls of the busways.
For straight runs, the busway walls include simple elongate flanges used to join the walls together. For corner or elbow joints, however, more is needed. Previously, elbow joints were formed from a pair of "L" shaped sheets of metal stock that effect housing side walls. The margins were double bent to form spacer portions and fastener portions, with the fastener portions engaging and being bolted to one another and the spacer portions spacing the enclosure side walls from one another. Gasket material between the fastener portions sealed the enclosure against intrusion of moisture. To facilitate the bending of the margins, the marginal portion of the material at the opposed corners of the bend was cut away to leave openings between the sealed fastener portions.
Previously these openings were closed by stamping four corner pieces from sheet metal and spot welding two corner pieces to each enclosure side wall, respectively, at the opposed corners of the bend. These corner pieces rested in positions substantially parallel to the enclosure side walls to extend the side walls, spacer portions and fastener portions over the openings. Gasket material placed between the corner pieces attempted to seal the corners against moisture, but often failed. The corner pieces were too flimsy to accept a separate bolt to clamp them together, and the corner pieces had to overlap the fastener portions for the spot welds. This left small sliver gaps at the edges of the fastener portions and under the corner pieces through which moisture often seeped into the enclosure. This moisture sometimes caused a short circuit between the busbars that led to unsafe conditions.
Stamping the corner pieces and spot welding them to the enclosure side walls required undesired additional manufacturing steps. The spot welding itself did not always seal the corner pieces to the enclosure walls; it sometimes left sliver gaps through which moisture could enter the enclosure.